The invention is applicable to the technical field of computer aided design (cad) and provides a method for drawing an unfolding drawing in Autocad (Auto Computer Aided Design) according to a torsion entity. The method comprises the following steps performed on an Autocad platform: automatically generating a spatial broken-line model by using ObjectARX according to the three-dimensional coordinates of each control point in a single-line model, and fitting the spatial broken-line model into a spatial grid curve through calculating; generating a node normal line on the broken-line model by using ObjectARX; automatically generating a torsion member bar entity model and a torsion node plate according to the broken-line model and the node normal line by using ObjectARX; drawing the cutting drawings, assembly drawings and mounting drawings of components and parts according to the torsion member bar entity model. According to the method, the torsion member bar entity model can be established in an efficient and accurate user-defined manner, and a three-dimensional model can be unfolded into a two-dimensional drawing through the torsion member bar entity model, so that the automatic generation of drawings is realized, the drawing efficiency is increased, the factory processing is facilitated, and the 1:1 numerically-controlled cutting for the parts can be realized.